Film platinum resistor dynamic total temperature probe comb for measuring unsteady flow field in narrow space

Abstract

The invention belongs to the technical field of dynamic temperature testing, and particularly relates to a film platinum resistor dynamic total temperature probe comb for measuring an unsteady flow field in a narrow space, which comprises a probe support rod, a positioning block, a probe head, a film platinum resistor, a circular pipeline and a lead hole. A round pipeline is arranged inside the probe supporting rod, a positioning block is arranged at the tail part of the probe supporting rod, the probe heads are ball-socket-shaped, the number of the probe heads is determined according to measurement requirements, lead holes are respectively formed in different spanwise measurement positions of the probe supporting rod and in the centers of the probe heads, the lead holes are communicated with the round pipeline, and thin film platinum resistors are arranged above the lead holes. And a film platinum resistor lead passes through the lead hole and the circular pipeline and is led out from the tail part of the probe. The film platinum resistor dynamic total temperature probe comb for measuring the unsteady flow field in the narrow and small space is calibrated, is suitable for measuring distribution of dynamic total temperature of the unsteady flow field in the narrow and small space of a turbomachine in the height direction of a blade, and can measure incoming flow parameters of multiple narrow and small space positions at the same time compared with an existing probe for measuring the dynamic temperature. The measurement time is shortened to the greatest extent, and the test cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of dynamic temperature testing, and specifically relates to a thin-film platinum resistor dynamic total temperature probe comb for measuring unsteady flow fields in narrow spaces. The present invention is suitable for measuring transient information of unsteady flow fields in narrow spaces of impeller machines. The core of the probe comb is to quickly and accurately measure and monitor the distribution of transient temperature of unsteady flow fields in subsonic narrow spaces of impeller machines along the blade height direction.

[0002] Compared with the existing temperature probes for measuring three-dimensional flow fields, the probe head is "I"-shaped, which can measure the flow field information in a narrow space without the help of a probe displacement mechanism to change the position of the measuring point. It can instantly complete the measurement of the temperature distribution of the incoming flow in the unsteady flow field in the narrow space of the impeller along the blade height direction, and reduce the test cost. Background Art

[0003] Due to the viscosity of the fluid, shock waves, the rotation of the rotor, the existence of the tip clearance, etc., especially at the inlet, outlet and interstage positions, in the face of complex and high-speed rotation, the rotor and the stator interfere with each other and the flow channel is narrow, and the internal flow presents non-uniform and asymmetric characteristics. This makes it very difficult to quickly and accurately obtain the change of the temperature field over time in the narrow space of the impeller. Due to the distortion of the inlet temperature of the impeller, the impeller experiment needs to measure the distribution of temperature along the blade height direction. In some impeller tests, due to the short effective test time of only a few minutes or even a few seconds, the existing temperature probe cannot complete the measurement of the distribution of the three-dimensional flow field parameters of the test piece inlet and outlet along the blade height direction within a few seconds, and it is difficult to install a displacement mechanism on some small and compact impeller testers. Therefore, in order to quickly and accurately obtain the transient temperature information of the unsteady flow field in the narrow space of the impeller, it is necessary to develop more targeted testing methods.

[0004] At present, thermocouple temperature probes are generally used. The probe displacement mechanism is used to drive the probe to different blade height positions for measurement. Since it is a single-point measurement, the probe needs to be moved to complete multi-point measurement. The experimental measurement time is long and the experimental cost is high. However, it is difficult to install a displacement mechanism on some small and compact impeller machinery testers. Thermocouple temperature sensors are often used to obtain dynamic temperature signals of the flow field. However, due to limited frequency, the thin-wire thermocouple temperature sensor with the highest frequency response cannot fully meet the test requirements of the transient temperature field of the unsteady flow field in the narrow space of the impeller under special working conditions. Compared with the thin-film platinum resistance temperature sensor, the accuracy of the thermocouple is lower. During long-term use, the thermocouple may drift due to material aging and thermoelectric effect, resulting in increased measurement errors and is easily affected by environmental factors.

[0005] Therefore, in order to quickly and accurately obtain the transient temperature field of the unsteady flow field in the narrow space of the impeller, it is urgent to develop a fast, high-precision, airflow-resistant, low-spatial-resolution, and low-flow-field-interference testing technology to achieve accurate measurement of the dynamic temperature of the unsteady flow field in a narrow space, and provide reliable measurement means and technical support for the high-performance design and optimization of the impeller machinery. Summary of the invention

[0006] The present invention discloses a thin film platinum resistor dynamic total temperature probe comb for measuring unsteady flow fields in a narrow space, comprising a probe support rod, a positioning block, a probe head, a thin film platinum resistor, a circular pipe, and a lead hole. A circular pipe is provided inside the probe support rod, a positioning block is provided at the tail of the probe support rod, and the probe head is a ball-and-socket type, the number of which is determined according to the measurement requirements, and is at least 3, respectively at different spanwise measurement positions of the probe support rod. A lead hole is provided at the center of the probe head, the lead hole is communicated with the circular pipe, a thin film platinum resistor is installed above the lead hole, and the lead wire of the thin film platinum resistor passes through the lead hole and the circular pipe and is led out from the tail of the probe.

[0007] In the calibration wind tunnel, a thin-film platinum resistor dynamic total temperature probe for measuring a wide range of airflow between turbine stages is calibrated over a wide range. The calibration speed range is 0.1 Mach to 1.4 Mach, the deflection angle range is -80° to 80°, and the pitch angle range is -40° to 40°. During the wind tunnel test calibration, two thin-film platinum resistors are used to measure the temperature simultaneously. The two thin-film thermal resistors are provided with different constant currents by a signal generator. The two resistors have different initial temperatures, but have the same convective heat transfer surface heat transfer coefficient X. The ratio of the heat flux density of the two thin-film platinum resistors under different working conditions can be obtained. The ratio of the heat flux density is defined as X and satisfies the following equation:

[0008] q1=h(T t -T w1 )

[0009] q2=h(T t -T w2 )

[0010]

[0011] Where, q1, q2——heat flux density of thin film thermal resistor, unit W / m 2 ; Tw1, Tw2——temperature measured by thin film thermal resistor, unit K; Tt——total temperature of the calibration wind tunnel inflow, unit K. The ratio X of heat flux density under different calibration conditions can be obtained by the above calibration method;

[0012] During the test measurement, when the incoming flow condition is known, the corresponding heat flux ratio X can be found from the calibration data. The total temperature T of the measured airflow can be calculated from the measured Tw1 and Tw2 data by the following formula: g :

[0013]

[0014] The dynamic total temperature probe and the calibration and measurement data processing method of the present invention can greatly improve the measurement accuracy of the dynamic total temperature.

[0015] The present invention provides a thin-film platinum resistor dynamic total temperature probe comb for measuring unsteady flow fields in a small space. The technical problems to be solved are: first, the problem of insufficient accuracy of existing dynamic temperature probe combs is solved. Second, the problem that existing temperature probe combs are limited by the low frequency response of traditional dynamic temperature sensors is solved. Third, in view of the problem that existing temperature probes cannot complete the distribution measurement of the temperature parameters of the three-dimensional flow fields at the inlet and outlet of the impeller machinery test piece along the blade height direction within a few seconds, compared with the existing temperature probes, it can simultaneously measure the incoming flow parameters of multiple spatial positions, which can shorten the measurement time to the greatest extent, complete the measurement of the incoming flow temperature distribution of the three-dimensional flow fields at the inlet and outlet of the impeller machinery test piece along the blade height direction, and reduce the test cost. Fourth, the problem that existing temperature probes cannot measure the flow field in a small space is solved.

[0016] The technical solution of the present invention is:

[0017] 1. A thin film platinum resistor dynamic total temperature probe comb for measuring unsteady flow fields in a narrow space, comprising a probe support rod (1), a positioning block (2), a probe (3), a right thin film platinum resistor (4), a left thin film platinum resistor (5), a circular pipe (6), and a lead hole (7), characterized in that: the probe support rod (1) has a circular pipe (6) inside, the probe support rod (1) has a positioning block (2) at the tail end, the probe head (3) is a ball-and-socket type, the number of which is determined according to measurement requirements, and is at least 3, and is respectively fixed at different spanwise measurement positions of the probe support rod (1), a lead hole (7) is opened at the center of the probe head (3), the lead hole (7) is communicated with the circular pipe (6), the right thin film platinum resistor (4) and the left thin film platinum resistor (5) are installed above the lead hole (7), and the leads of the right thin film platinum resistor (4) and the left thin film platinum resistor (5) pass through the lead hole (7) and the circular pipe (6) and are led out from the tail end of the probe.

[0018] 2. The probe support rod (1) is a cylinder, and the diameter of the cylinder is d, and the value range of d is 2 mm ≤ d ≤ 10 mm. The probe support rod (2) is provided with a circular pipe (6) along the axial inside, and the diameter of the circular pipe is a, and the value range of a is 1 mm ≤ a ≤ 8 mm. The thin film platinum resistance wire passes through the lead hole and is connected to the external collection equipment through the circular pipe (6).

[0019] 3. The probe head (3) is integrated with the probe support rod (1). The probe head (3) is an ellipsoidal groove, or a spherical groove can be selected. The groove depth is h, and the value range of h is 2 mm ≤ h ≤ 5 mm. The projection of the probe head (3) along the vertical axis of the probe support rod is parallel to the plane of the positioning block. The probe head (3) is made of insulating and heat-insulating material to reduce the thermal conductivity error during measurement and improve the measurement accuracy and frequency response of the probe.

[0020] 4. The center of the lead hole (7) coincides with the center of the probe head (3), and the diameter is 0.2 mm to 1 mm.

[0021] 5. The right thin-film platinum resistor (4) and the left thin-film platinum resistor (5) are installed on the lead hole. The right thin-film platinum resistor (4) and the left thin-film platinum resistor (5) are miniature four-wire thin-film platinum resistors with a length of 0.5 mm to 3 mm, a width of 0.1 mm to 1.5 mm, and a thickness of 0.01 mm to 0.2 mm. The four-wire measurement can effectively eliminate the influence of the lead resistance on the measurement result, improve the measurement accuracy, and ensure the stability and accuracy of the data.

[0022] 6. The installation distance between the right thin film platinum resistor (4) and the left thin film platinum resistor (5) is x, and the value range of x is 0.2 mm ≤ x ≤ 1 mm.

[0023] 7. The cross section of the positioning block (2) is a regular quadrilateral, and the cross section shape can be a regular pentagon, a regular hexagon or a regular heptagon. The center line of the cross section is in the same plane as the axis of the probe support rod (1). The thickness of the positioning block is a, and the value range of a is 2 mm ≤ d ≤ 10 mm. The distance between the positioning block (2) and the bottom of the probe support rod (1) is b, and the value range of b is 5 mm ≤ b ≤ 20 mm.

[0024] The present invention provides a dynamic total temperature probe comb of a thin film platinum resistor for measuring a subsonic unsteady flow field, which has the following beneficial effects:

[0025] Beneficial effect 1: The present invention has been calibrated in a standard wind tunnel, has high measurement accuracy and fast response speed, the sensing part is not affected by the structure of the probe itself, and first senses the pulsation of the incoming flow, the flow field information is not distorted, and the measurement accuracy is high. Through the precise calibration process, it is ensured that the response of the thin film platinum resistor at different temperature points is accurate and reliable, and when measuring, only the incoming flow parameters need to be obtained, and there is no need to understand the physical properties of the measured medium.

[0026] Beneficial effect 2: The present invention is based on the design of a double-thin-film platinum resistor. The two thin-film platinum resistors compensate each other during temperature measurement, significantly improving the frequency response performance of the probe. Compared with traditional sensors, the double-thin-film platinum resistor can respond to temperature changes more quickly and adapt to the measurement requirements of transient temperature fields, especially under complex working conditions at the inlet and outlet of the impeller and between stages, and can accurately capture the dynamic changes of temperature.

[0027] Beneficial effect three: The present invention is suitable for the distribution of the three-dimensional flow field parameters along the blade height direction in the narrow space of the impeller machinery. Compared with the existing temperature probe for measuring the three-dimensional flow field, it can simultaneously measure the flow parameters of multiple spatial positions, which can shorten the measurement time to the greatest extent, complete the measurement of the distribution of the three-dimensional flow field parameters of the impeller machinery inlet and outlet along the blade height direction, and reduce the test cost.

[0028] Beneficial effect four: The structure of the present invention is simple and compact, is "I"-shaped, and has a small size, which improves the spatial resolution of the probe and can be easily inserted into the narrow space of the impeller machinery for testing.

[0029] Beneficial effect five: The probe of the present invention has a self-positioning function, the positioning block forms a positioning reference, the probe is easy and convenient to install, does not need to be rotated during measurement, has no periodicity requirements on the measured flow field, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a schematic structural diagram of a thin-film platinum resistor dynamic total temperature probe comb for measuring an unsteady flow field in a narrow space according to an embodiment of the present invention.

[0031] Figure 2 yes Figure 1 Top view of the .

[0032] Figure 3 yes Figure 1 Side view of.

[0033] Figure 4 yes Figure 1 C-section view.

[0034] Figure 5 yes Figure 1 B-direction cross-sectional view.

[0035] Figure 6 yes Figure 1 A-section view.

[0036] Figure 7 yes Figure 6 A partial enlarged view of .

[0037] Among them: 1-probe support rod, 2-positioning block, 3-probe, 4-right thin film platinum resistor, 5-left thin film platinum resistor, 6-circular pipe, 7-lead hole. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with the accompanying drawings and specific implementation examples so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0039] like Figures 1 to 7The present invention shows a thin film platinum resistor dynamic total temperature probe comb for measuring unsteady flow fields in a narrow space, which is composed of a probe support rod (1), a positioning block (2), a probe (3), a right thin film platinum resistor (4), a left thin film platinum resistor (5), a circular pipe (6), and a lead hole (7). The present invention is characterized in that: the probe support rod (1) has a circular pipe (6) inside, the tail of the probe support rod (1) has a positioning block (2), the probe head (3) is a ball-and-socket type, the number of which is determined according to the measurement requirements, and is at least 3, and is respectively fixed at different spanwise measurement positions of the probe support rod (1), a lead hole (7) is opened at the center of the probe head (3), the lead hole (7) is communicated with the circular pipe (6), the right thin film platinum resistor (4) and the left thin film platinum resistor (5) are installed above the lead hole (7), and the leads of the right thin film platinum resistor (4) and the left thin film platinum resistor (5) pass through the lead hole (7) and the circular pipe (6) and are led out from the tail of the probe;

[0040] The probe support rod (1) is a cylinder, and the diameter of the cylinder is d, and the value of d is 10 mm; the probe support rod (2) is provided with a circular pipe (6) along the axial direction, and the diameter of the circular pipe is a, and the value of a is 5 mm. The thin film platinum resistance wire passes through the lead hole and is connected to the external collection equipment through the circular pipe (6);

[0041] The probe head (3) is integrated with the probe support rod (1), and the probe head (3) is an ellipsoidal groove, and the groove depth is h, and the value of h is 2 mm; the projection of the probe head (3) along the direction perpendicular to the axis of the probe support rod is parallel to the plane of the positioning block, and the probe head (3) is made of insulating and heat-insulating material to reduce the thermal conductivity error during measurement and improve the measurement accuracy and frequency response of the probe;

[0042] The center of the lead hole (7) coincides with the center of the probe head (3), and the diameter is 0.5 mm;

[0043] The right thin-film platinum resistor (4) and the left thin-film platinum resistor (5) are installed on the lead hole. The right thin-film platinum resistor (4) and the left thin-film platinum resistor (5) are miniature four-wire thin-film platinum resistors with a length of 1.5 mm, a width of 1 mm, and a thickness of 0.1 mm. The four-wire measurement can effectively eliminate the influence of the lead resistance on the measurement result, improve the measurement accuracy, and ensure the stability and accuracy of the data.

[0044] The installation distance between the right thin film platinum resistor (4) and the left thin film platinum resistor (5) is x, and the value of x is 0.5 mm;

[0045] The cross section of the positioning block (2) is a regular quadrilateral, the center line of the cross section is in the same plane as the axis of the probe support rod (1), the thickness of the positioning block is a, the value of a is 10 mm, the distance between the positioning block (2) and the bottom of the probe support rod (1) is b, and the value of b is 20 mm;

[0046] In the calibration wind tunnel, a thin-film platinum resistor dynamic total temperature probe for measuring a wide range of airflow between turbine stages is calibrated over a wide range. The calibration speed range is 0.1 Mach to 1.4 Mach, with an interval of 0.1 Mach, the deflection angle range is -80° to 80°, with an interval of 5°, and the pitch angle range is -40° to 40°, with an interval of 5°. During the wind tunnel test calibration, two thin-film platinum resistors are used to measure the temperature simultaneously. The two thin-film thermal resistors are provided with different constant currents by a signal generator. The two resistors have different initial temperatures, but have the same convective heat transfer surface heat transfer coefficient X. The ratio of the heat flux density of the two thin-film platinum resistors under different working conditions can be obtained. The ratio of the heat flux density is defined as X, and satisfies the following equation:

[0047] q1=h(T t -T w1 )

[0048] q2=h(T t -T w2 )

[0049]

[0050] Where, q1, q2——heat flux density of thin film thermal resistor, unit W / m 2 ; Tw1, Tw2——temperature measured by thin film thermal resistor, unit K; Tt——total temperature of the calibration wind tunnel inflow, unit K. The ratio X of heat flux density under different calibration conditions can be obtained by the above calibration method;

[0051] During the test measurement, when the incoming flow condition is known, the corresponding heat flux ratio X can be found from the calibration data. The total temperature T of the measured airflow can be calculated from the measured Tw1 and Tw2 data by the following formula: g :

[0052]

[0053] The dynamic total temperature probe and the calibration and measurement data processing method of the present invention can greatly improve the measurement accuracy of the dynamic total temperature.

Claims

1. A thin film platinum resistor dynamic total temperature probe comb for measuring unsteady flow fields in a narrow space, comprising a probe support rod (1), a positioning block (2), a probe (3), a right thin film platinum resistor (4), a left thin film platinum resistor (5), a circular pipe (6), and a lead hole (7), characterized in that: The probe support rod (1) has a circular pipe (6) inside, and a positioning block (2) is provided at the tail of the probe support rod (1). The probe head (3) is a ball-and-socket type, and the number of the probe heads (3) is determined according to the measurement requirements, and is at least three, and is respectively fixed at different spanwise measurement positions of the probe support rod (1). A lead hole (7) is provided at the center of the probe head (3), and the lead hole (7) is communicated with the circular pipe (6). A right thin-film platinum resistor (4) and a left thin-film platinum resistor (5) are installed above the lead hole (7), and the leads of the right thin-film platinum resistor (4) and the left thin-film platinum resistor (5) pass through the lead hole (7) and the circular pipe (6) and are led out from the tail of the probe. The probe support rod (1) is a cylinder, and the diameter of the cylinder is d, and the value range of d is 2 mm ≤ d ≤ 10 mm; the probe support rod (2) is provided with a circular pipe (6) along the axial direction, and the diameter of the circular pipe is a, and the value range of a is 1 mm ≤ a ≤ 8 mm. The thin film platinum resistance wire passes through the lead hole and is connected to the external collection equipment through the circular pipe (6); The probe head (3) is integrated with the probe support rod (1), the probe head (3) is an ellipsoidal groove, and a spherical groove can also be selected, the groove depth is h, and the value range of h is 2 mm≤h≤5 mm; the projection of the probe head (3) along the vertical axis direction of the probe support rod is parallel to the plane of the positioning block, and the probe head (3) is made of insulating and heat-insulating materials to reduce the thermal conductivity error during measurement and improve the measurement accuracy and frequency response of the probe; The center of the lead hole (7) coincides with the center of the probe head (3), and the diameter is 0.2 mm to 1 mm; The right thin-film platinum resistor (4) and the left thin-film platinum resistor (5) are installed on the lead hole. The right thin-film platinum resistor (4) and the left thin-film platinum resistor (5) are miniature four-wire thin-film platinum resistors with a length of 0.5 mm to 3 mm, a width of 0.1 mm to 1.5 mm, and a thickness of 0.01 mm to 0.2 mm. The four-wire measurement can effectively eliminate the influence of the lead resistance on the measurement result, improve the measurement accuracy, and ensure the stability and accuracy of the data. The installation distance between the right thin film platinum resistor (4) and the left thin film platinum resistor (5) is x, and the value range of x is 0.2 mm ≤ x ≤ 1 mm; The cross section of the positioning block (2) is a regular quadrilateral, and the cross section shape can be a regular pentagon, a regular hexagon or a regular heptagon. The center line of the cross section is in the same plane as the axis of the probe support rod (1). The thickness of the positioning block is a, and the value range of a is 2 mm ≤ d ≤ 10 mm. The distance between the positioning block (2) and the bottom of the probe support rod (1) is b, and the value range of b is 5 mm ≤ b ≤ 20 mm. The present invention proposes a calibration and measurement data processing method based on a thin film platinum resistor dynamic total temperature probe comb for measuring an unsteady flow field in a narrow space. A thin film platinum resistor dynamic total temperature probe for measuring a wide airflow range between turbine stages is calibrated over a wide range in a calibration wind tunnel. The calibration speed range is 0.1 Mach to 1.4 Mach, the deflection angle range is -80° to 80°, and the pitch angle range is -40° to 40°. During the wind tunnel test calibration, two thin film platinum resistors are used to measure the temperature simultaneously. The two thin film thermal resistors are provided with different constant currents by a signal generator. The two resistors have different initial temperatures but have the same convective heat transfer surface heat transfer coefficient X. The heat flux density ratio of the two thin film platinum resistors under different working conditions can be obtained. The heat flux density ratio is defined as X and satisfies the following equation: q1=h(T t -T w1 ) q2=h(T t -T w2 ) Where, q1, q2——heat flux density of thin film thermal resistor, unit W / m 2 ; Tw1, Tw2——Temperature measured by thin film thermal resistor, unit K; Tt——total temperature of the calibrated wind tunnel inflow, unit K. The ratio X of heat flux density under different calibration conditions can be obtained through the above calibration method; During the test measurement, when the incoming flow condition is known, the corresponding heat flux ratio X can be found from the calibration data. The total temperature T of the measured airflow can be calculated from the measured Tw1 and Tw2 data by the following formula: g : The dynamic total temperature probe and calibration and measurement data processing method of the present invention can greatly improve the measurement accuracy of the dynamic total temperature, and during measurement, only the incoming flow parameters need to be obtained without understanding the physical property parameters of the measured medium.

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